The draft has already been agreed by the five veto-wielding members of the council - Britain, China, France, Russia and the US - meaning it is very likely to be adopted.

Britain, France sand Germany, co-sponsors of the text, say they are confident that they have sufficient support among the council's 10 non-permanent members for a resolution to pass.

However, Indonesia, Libya, South Africa and Vietnam, all non-permanent council members, have said that further sanctions may be unnecessary.

South African view

Abdul Minty, South Africa's envoy to the International Atomic Energy Agency (IAEA), the nuclear watchdog, said the latest report by Mohamed ElBaradei, the agency's chief, showed "increasing confidence that Iran does not intend to use its nuclear programme for military purposes".

But Nicolas Sarkozy, France's president, called on Thabo Mbeki, South Africa's president, to back the sanctions draft on Thursday, during a visit to Cape Town, calling it "necessary to do something to avoid the worst".

Vitaly Churkin, Russia’s ambassador to the UN, said the council had to take a tough line against Iran, despite Moscow's close energy and economic ties.

Manouchehr Mottaki, Iran's foreign minister, called the Security Council's charges "baseless", in a letter to Ban Ki-Moon, the UN's secretary-general.